Add states to metadata.

States are dynamically changing values. For now
none of them have implementations; they're all fixed
values.

BUG: 30140438
TEST: unit tests pass
Change-Id: I60f97fce5db4542e6b77694bb323934e32eab9f6
diff --git a/modules/camera/3_4/metadata/state.h b/modules/camera/3_4/metadata/state.h
new file mode 100644
index 0000000..54f66e4
--- /dev/null
+++ b/modules/camera/3_4/metadata/state.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef V4L2_CAMERA_HAL_METADATA_STATE_H_
+#define V4L2_CAMERA_HAL_METADATA_STATE_H_
+
+#include "../common.h"
+#include "metadata_common.h"
+#include "partial_metadata_interface.h"
+#include "state_delegate_interface.h"
+
+namespace v4l2_camera_hal {
+
+// A State is a PartialMetadata that only has a single dynamic value.
+template <typename T>
+class State : public PartialMetadataInterface {
+ public:
+  State(int32_t tag, std::unique_ptr<StateDelegateInterface<T>> delegate)
+      : tag_(tag), delegate_(std::move(delegate)){};
+
+  virtual std::vector<int32_t> StaticTags() const override { return {}; };
+  virtual std::vector<int32_t> ControlTags() const override { return {}; };
+  virtual std::vector<int32_t> DynamicTags() const override { return {tag_}; };
+
+  virtual int PopulateStaticFields(
+      android::CameraMetadata* metadata) const override;
+  virtual int PopulateDynamicFields(
+      android::CameraMetadata* metadata) const override;
+  virtual int PopulateTemplateRequest(
+      int template_type, android::CameraMetadata* metadata) const override;
+  virtual bool SupportsRequestValues(
+      const android::CameraMetadata& metadata) const override;
+  virtual int SetRequestValues(
+      const android::CameraMetadata& metadata) override;
+
+ private:
+  int32_t tag_;
+  std::unique_ptr<StateDelegateInterface<T>> delegate_;
+};
+
+// -----------------------------------------------------------------------------
+
+template <typename T>
+int State<T>::PopulateStaticFields(android::CameraMetadata* metadata) const {
+  HAL_LOG_ENTER();
+  return 0;
+}
+
+template <typename T>
+int State<T>::PopulateDynamicFields(android::CameraMetadata* metadata) const {
+  HAL_LOG_ENTER();
+
+  T value;
+  int res = delegate_->GetValue(&value);
+  if (res) {
+    return res;
+  }
+  return UpdateMetadata(metadata, tag_, value);
+};
+
+template <typename T>
+int State<T>::PopulateTemplateRequest(int template_type,
+                                      android::CameraMetadata* metadata) const {
+  HAL_LOG_ENTER();
+  return 0;
+};
+
+template <typename T>
+bool State<T>::SupportsRequestValues(
+    const android::CameraMetadata& metadata) const {
+  HAL_LOG_ENTER();
+  return true;
+};
+
+template <typename T>
+int State<T>::SetRequestValues(const android::CameraMetadata& metadata) {
+  HAL_LOG_ENTER();
+  return 0;
+};
+
+}  // namespace v4l2_camera_hal
+
+#endif  // V4L2_CAMERA_HAL_METADATA_STATE_H_